1. Field of the Invention
This invention relates generally to a washout system for a transit concrete mixer drum and, more particularly, it relates to a washout system for a transit concrete mixer which is extendible into the mixer drum for delivering pressurized water into the interior of the mixer drum.
2. Description of the Prior Art
Transit concrete mixer drums typically consist of a large mixer drum with internal fins arranged in a corkscrew pattern. The mixer drum is mounted horizontally and rotated about a center axis. As the mixer drum turns, the fins force the concrete into or out of the drum depending on the direction of rotation.
Unfortunately, current concrete mixer drum design does not allow complete removal of the concrete. In fact, when the mixer drum is loaded with fresh concrete and then unloaded, a small amount of concrete remains inside the mixer drum adjacent the fins. In an attempt to remove the remaining concrete, the concrete truck driver or operator will then fill the mixer drum with water in an attempt to wash the remaining concrete from the mixer drum. However, since concrete trucks only carry a maximum of one hundred and twenty-five (125) gallons of water which must be used to water down the load before concrete unloading, the remaining amount of water is not sufficient to clean the mixer drum, especially on the side of the fins facing toward the front of the concrete truck.
Another alternative to remove the concrete prior to hardening within the mixer drum is to load a large amount of water into the mixer drum upon the concrete truck returning to the operation site. Unfortunately, the water travels directly to the front of the mixer drum and does not wash the back side of the fins. The operator typically can not reach far enough into the mixer drum to reach the back side of the fins.
The concrete remaining in the mixer drum which is not washed out, the concrete will harden inside the mixer drum. Over time, layers of concrete build up until large amounts of dried, hardened concrete is present inside the mixer drum; reducing the mixer drum volume and mixing with the fresh concrete. The hardened concrete must now be removed by mechanical or chemical means. Neither of the mechanical means nor chemical means are an attractive method for the concrete truck operator due to high costs and environmental hazards. For instance, mechanical means typically requires a person to physically enter the drum with a jackhammer to physically remove the hardened concrete. Chemical means, on the other hand, typically requires dangerous chemical which can contaminate the environment or require special handling and safety procedures.
Accordingly, there exists a need for a transit concrete mixer drum washout system which effectively removes concrete from the inside of a mixer drum prior to the concrete hardening therein. Additionally, a need exists for a transit concrete mixer drum washout system which does not require either expensive mechanical removal of hardened concrete or dangerous chemicals harmful to the environment. Furthermore, there exists a need for a transit concrete mixer drum washout system which is extendible into the mixer drum to inject pressurized water to all areas thereby removing the concrete therein prior to hardening.